Mechanical jack



Jan. 2, 1934. E. F. GREEN ET AL,

MECHANICAL JACK Filed Sept. 30, 1930 2 Sheets-Sheet l l Vv/ Jam 2, 1934-E. F. GREEN Er AL 1,942,244

MECHANICAL JACK Filed Sept. 30, 1930 2 Sheets-Sheet 2 Patented Jan. 2,

iJiTED STATES PANT @EC MECHANICAL JACK Application September 30, 1930Serial No. 485,497

18 Claims.

This invention relates to lifting jacks, particularly those of the trucktype commonly used in garages and repair shops for lifting automobiles,and has for its general object the provision of an improved jack of thistype which is entirely mechanical, of simple and compact construction,easy to handle and not likely to get out of order, and in which the loadmay be lowered in stepby-step manner,

With this object in View we provide a jack having an elongatedfour-wheeled frame which carries at its rear end a load supporting tableor saddle, and adjacent its front end a hand lever or tongue and a pawland ratchet mechanism operably connected thereto and adapted to actuatea rack bar connected to the main lever, which is of bell crank type,reversing mechanism being associated with said pawl and ratchetmechanism, whereby an oscillation of the handle causes a step-by-stepmovement of the rack bar in either direction, as desired, to raise orlower the table.

In the accompanying drawings we have illustrated a 4jaclr embodying ourinvention, and we will hereinafter describe the construction andoperation of this form of jack with particularity, with theunderstanding, however, that we do not intend to restrict the scope oiour invention to the specific details shown and described for it will beobvious to those skilled in the art that changes and modifications inthese details may be made without substantially varying the mode ofoperation of the invention or the basic principles of construction.

In the drawings:

Figure l is a plan view of the jack;

Figure 2 is a side elevation thereof;

Figure 3 is a plan view of one member of the rack bar support;

ligure 4 is a side elevation thereof;

Figure 5 is a detail View illustrating the pawl and ratchet mechanismand the reversing cam lever associated therewith.

Figure 6 is a section taken on line 6 6 of Figure 2.

The frame of the jack, as shown in Figures 1 and 2, comprises a pair ofspaced parallel bars l0 secured together at their rear and front ends,respectively, by an axle sleeve l1 and a bolt 12 carrying a spacingsleeve against which the bars 50 are clamped by nuts 13. Additional tiemembers for the side bars are provided by sleeved bolts i4 and l5. Thisframe is supported at its rear or load carrying end by rollers 16 havingball bearings on the projecting ends of an axle 17 55 supported insleeve 1l.A Rearwardly of its front end the frame is supported bycastors 18 carried by laterally projecting brackets 19 riveted to theouter sides of the frame bars l0.

The load supporting table 20, mounted adjacent the rear end of the framefor vertical raising and lowering movements, has an integral pedestal,or stem, formed with laterally projecting trunnions 2l which are carriedin the forked ends of a pair of triangular lever castings 22, thesecastings being fulcrumed near their apexes on a 'bolt 23 secured inapertures of a pair of plate projections 24 made integral with the framebars 10 preferably by welding. The two lever castings 22 are tiedtogether and held in proper spaced relation, to form a rigid structure,by bolts 25 and a spacing plate 26, the bolts passing through the plateand castings and having nuts on their projecting ends for clamping theplate between the castings. The usual parallel motion of table 20 iseiected by two drag links 27 pivoted at one end to the projections 24 onan axis 30 and pivoted Yat their other ends to the ends of a transverserod 3l secured in forwardly extending lugs of the sraddle stem.Supported in alined bearings formed, in the rear base angles of casting22 is a cross bolt 33 secured from displacement by cotter ypins 34, andpivoted to this bolt is a rack bar 35 which extends centrally of theframe and is adapted to project forwardly of the front end thereof whenthe saddle is in its lowest position;

Rack bar 35 is slidably supported in a rack block formed of two similarcastings 36 and 37 which are mounted in the frame to rock on atransverse axis, the castings for this purpose being formed with coaxialtrunnions 38 adapted to pivo-t in bearings provided in the side bars 10.The right hand rack block casting 37 is clearly illustrated in Figures 3and 4, the left hand casting, except for unimportant details, being ofthe same form and construction. It will be observed that the casting isformed with an outwardly projecting top flange 39 which has a maximumwidth directly above trunnion 38, and vis provided at its rear and frontcorners with apertures 40 and 41, respectively. Extending through theseapertures are bolts 42 and 43 and carried by these bolts are rollers 44and 45 which engage the iiat top side of the Arack bar. The lower sideof the rackbar, on which the vteeth are formed,

is supported by ledges 46 and 47 formed integrally 105 with castings 35and 37 and located substantially directly beneath the rollers. The rackbar is thus supported for free longitudinal sliding movement in the rackblock, and the rack block itself I being trunnioned on a transverse axispermits the rack bar to assume different angular positions asnecessitated in its longitudinal movement by reason of its connectionwith the main elevating levers 22.

The pawl and ratchet mechanism for operating the rack bar includes apawl lever located between the rack block castings 36 and 37 andiulcrumed thereto on an axis which is coincident with the trunnion axisof said castings, the lever 50 being formed with pivots 5l seated inbearings 52 provided in the inner faces of the castings. Lever 50 isforked so as to straddle the rack bar, and pivoted in the fork below therack bar is a driving pawl 58 engaging the rack teeth on the under sideof the rack bar. Pawl 53 carries adjacent its free end a laterallyextending pin 54 which projects to the outside of the rack block casting37 and has attached near its outer end the lower end of a contractilespring 55 the upper end of which is secured in the eye of a cotter pin56 fixed to flange 39 or casting 37. A holding pawl 57 is pivoted to apin 58 secured in an aperture or" a depending lug 59 of the right rackblock casting. This holding pawl carries a laterally projecting pin 6oextending to the outside of the casting corresponding to the pin 54 ofelevating and lowering pawl 53 and connected to the lower end or" aspring 6l having its upper end secured to cotter pin 56.

For manually oscillating the pawl lever 50 there is provided a handlever composed of two spaced members 62 pivoted on the bolt l2, bars 63bolted in sockets of said members, and a cross bar 64 connecting theupper ends of bars 63. Members 62 are formed with rearwardly projectinglugs 65 having inwardly projecting bosses 66 in which is supported a pin67 pivotally carrying one end of a link 68, the other end of which `isformed with one or more holes 69. Link 68 is received in the bifurcatedupper end of lever 58 and is pivoted therein by a pin 70 which isYadapted to pass through any one of the holes 69.

Pin 70 passes through a laterally projecting barrel 7l formed integrallywith lever 50 and housing a coil spring 72 which surrounds the pin andtends to hold it projected through the hole in link 68. Pin 70 extendsfrom the housing and carries a knob 73 by means of which it may beretracted whenever it is desired to adjust theeffective length of thelink by passing the pin through another hole therein. The handle is heldnormally in the position shown in Fig. 2 by a coil spring 74 whichconnects the left hand member 62 of the handle to a small lug 74a risingfrom the left hand rack block casting 36.

Mechanism for reversing the step-by-step jmo'vernent of the rack barupon oscillation of the hand lever includes a cam lever 75 which ispivoted on the outer end of a pin 76 carried in apertures 77 of the rackblock castings. This lever consists of a forwardly projecting cam armand an upwardly extending arm through which passes al rod 78. This rodhas an angular forward extremity received in a hole formed in a footlever 79 which is fulcrumed on a pin 80 secured to the right hand framebar l0, this lever being provided with laterally extending projections,or pedals, 8l and 82 at its two ends by means of which it may beconveniently rotated in opposite directions by the foot of the operator.Rod 78 extends rearwardly past lever 75 and carries a coil spring 83bearing at one end against the upright arm of lever 75 and at its otherend against an adjustable seat 84 on the rod. It will be observed thatthe cam arm of lever 75 overlies pins 54 and 60 on the driving andholding pawls and is adapted to bear thereon with a yielding pressuregoverned by spring 83, for a purpose to be presently explained.

Assuming the operating elements of the jack to be in their normalpositions, as shown in Figure 2, that is, the positions assumed when thetable 20 is in its lowest position, and that the table 20 has beenbrought beneath the object to be raised a mere quick rearward pressureon the front end of rack bar 35, the operation of the jack in raisingtheobject is carried out in an obvious manner. The operator grasping thehandle bar 64 pulls the hand lever forwardly, or to the left, againstthe tension of spring 74, causing the pawl lever 5G to be rotatedcounter-clockwise and pawi 53 to be projected rearwardly while engaginga tooth of the rack bar, whereby the rack bar is moved rearwardly andthe table lever 22 rotated in a counter-clockwise direction through asmall angle. At the completion of this movement the holding pawl 57clicks over a 'tooth of the rack bar and upon return of the hand leverthe rack bar and table will be held from retrograde Inoveinent. Thus byoscillating the hand lever the rack bar is moved rearwardly and thetable isVA raised step-by-step. It will be observed that as the rack barmoves rearwardly, its pivot connection with main lever 22 nieves alongan arc centered at axis 23, that is, thev movement oi the L65 rearwardend of the rack bar has a vertical cornponent which causes the bar toassume positions at various angles to a horizontal plane. When the tableis in its lowest position, the rack bar, as shown in Figure 2, isinclined at a small angle tovii' the horizontal. When the. pivotconnection is vertically below the iulcrum axis 23 the rack bar has itsmaximum inclination; and when the table is in fully raised position therack bar is substantially horizontal, and extends only a fraction of aninch rearwardly of the roller 44 on Vthe rackblock. The trunnioned rackb-lock freely permits the rack bar to assume any angular position withinthe range of its movement. it is to be noted that during the raisingmovement the cam ign lever 75 merely rests on the pins 54 and 60 of thedriving and holding pawls without exerting any substantial pressurethereon, since the foot lever 79 is at this time in such position thatspring 83 is not compressed against the upstanding arm of the cam lever75. Y

The reverse operation, or the lowering of the load, is effected asfollowsr--`he operator presses on the projection 82 or" the foot levercausing rotation of the lever in a counter-clockwise direction andthereby drawing rod 78 forwardly, or to the left in Figure 2, thuscompressing spring 83 against the upstanding arin of cam lever 75. Therotation of the foot lever is continued until thepivot connection of rod78 therewith is brought slightly below the fulcrurn of the lever,whereupon the parts will be yieldingly held in such position by thetendency of spring 83 to draw rod 7 8 to the right. There is thusapplied to the cano lever a spring pressure tending to move the cam tarm of the lever downwardly. If there is no load on the table thisspring pressure is suiiicient to overpower the springs 55 and 6l holdingthe driving and holding pawls engaged with the rack bar, and hence therack bar will be released and the j, table will fall to its lowestposition immediately upon application of pressure by spring 83. However,if the saddle is sustaining a load the spring pressed cam lever does notexert suiiicient pressure to overcome the frictional resistance betweenFil the pawls and the rack bar plus the strength of the springs and 61,and under this condition the table can only be lowered with astep-by-step movementJ by oscillation of the handle. This step-by-steplowering movement is effected in the following mannen-Moving the handlever tothe left from the position shown in Figure 2 will cause thedriving pawl 53 to move the rack bar a step forward and will bring pin54 on this lever under a recess 85 formed on the under face of the camever,` see particularly Figure 5. This' movement of course takes theload olf the. holding pawl 57 and therefore permits the cam lever tothrow out the holding pawl as soon as the pin 54 has been brought intothe recess 85, as shown in dotted lines in Figure 5. The hand lever isnow moved to the right, moving pawl 53 to the left and with it the rackbar, pawl 53 now sustaining the load. As pawl 53 moves to the left, pin54 engages the inclined surface 86 of the cam lever and cams said leverupwardly, permitting the holding pawl 57 to be drawn by its spring intoengagement with the rack bar and when the holding pawl has fully engagedthe rack bar tooth and taken the load from the driving pawl the pin 54on the latter will have passed on to the end surface 87 of the cam leverand the driving pawl will therefore be forced downv out of engagementwith the rack bar, the movement of the cam lever being stopped by itsengagement with pin of the holding pawl. This downward movement of thecam lever places the cam surfaces thereof engaged by the pin 54 of thedriving pawl in such position as tocause this pawl to move over the racktooth it had just previously engaged and to come into engagement with anadjacent tooth when the pawl is again moved rearwardly, or to the right.Thus the oscillation of the hand lever effects a step-by-step reversemovement of the rack bar and a corresponding lowering of the load.

What we claim is:

l. A jack comprising a frame, a lever fulcrumed on the frame, a liftingtable supported by an arm of said lever, a rack bar pivoted to anotherarm of the lever, a support on which said bar is slidable, said supportbeing pivoted to the frame to permit the bar to assume inclinedpositions, and pawls cooperating with the bar for actuating said barstep-by-step in either direction.

2. A jack comprising a frame, a lever fulcrurned on the frame, a liftingtable supported by an arm of said lever, a rack bar pivoted to anotherarm of the lever, a support on which said bar is slidable, said supportbeing pivoted to the frame on an axis substantially parallel to the ful-Crum axis of said lever, and actuating means for the bar, meansincluding a pawl carried by said support said means cooperating toadvance the bar to raise the table and cooperating to retract the bar tolower the table.

3. A jack comprising a wheeled frame, a lever fulcrumed on the frame, alifting table supported by an arm of said lever, a rack bar pivoted toanother arm of the lever, a support in which said rack bar is slidable,said support being pivoted to the frame on an axis substantiallyparallel to the fulcrum axis of said lever, a pawl lever engaging saidrack bar pivoted to said support on an axis substantially coincidentwith the pivot axis of said support, a hand lever fulcrumed to theframe, and a link connecting the hand lever to the pawl lever.

4. A jack comprising an elongated wheeled frame, a lever fulcrumed tothe frame on a transverse axis, a lifting table supported by' an arm ofsaid lever, a-rack bar: pivoted to another' arm of the lever andextending centrally of thef frame, a support iin which bar is slidablymounted., said support being trunnionedto the framev on an axissubstantially parallel with the fulcrum axis of said lever, pawl andratchetl mechanism. carried by said support and a hand lever fulcrumedto the frame and. connected to said mechanism.

5. A jack comprising an elongated wheeled frame comprising spacedparallel side bars having transversely alined projections rising fromtheir upper sides adjacent the forward ends thereof, a lever comprisingtriangular side members fulcrumed adjacent their apexes tol saidprojections, a lifting table having trunnions supported in the forwardends of said lever members, a pin connecting the rear ends of said levermembers, a bar pivoted to said pin, and'v means for moving said barlongitudinally to raise and lower said table.

6. A jack comprising an elongated wheeled frame including spacedparallel side bars having transversely alined projections rising fromtheir upper sides adjacent the forward ends thereof, a lever comprisingtransversely spaced triangular members fulcrumed adjacent their apexesto said projections, a lifting table having trunnions supported in theforward ends of said triangular members, a pin connecting the rear endsof said members, a bar pivoted on said pin and extend.- ing centrallybetween said side bars, a. support iny which said bar is slidablymounted, said support having trunnions supported in said side bars,operating mechanism for said bar mounted on said support, and a handlever connected to said mechanism and fulcrumed to said side barsadjacent the rear ends thereof.

7. A jack comprising an elongated wheeled frame including spacedparallel bars having transversely alined projections rising from theirupper sides adjacent the forward ends thereof, a lever composed ofspaced triangular members fulcrumed adjacent their apexes to saidprojections, means for rigidly securing said members to- "f gether, alifting table having trunnions supported in the forward ends of saidmembers, a pair `of links pivoted at one end to said projections and attheir other ends to depending forwardly extending portions of said tableto objg.;

tain parallel movement of the table, a pin connecting the rear ends ofsaid triangular members, ar bar pivoted to said pin, and means foractuating said bar to raise and lower the table.

8. A jack comprising a frame, a lever fulf' crumed on the frame, alifting table supported by an arm of said lever, a rack bar pivoted toanother arm of the lever, means for slidably supporting said barcomprising4 two transversely spaced similar members having coaxialtrunnions pivoted to said frame and having inwardly extending ledges onwhich said rack bar rests, transverse pins secured in the front and rearupper cornersv of said members and carrying rollers engaging the topside of said bar, a bifurcated pawl lever straddling said bar andpivotally supported by said members on an axis substantially coincidentwith the trunnion axis thereof, a driving pawl pivoted in the bifurcatedlower end of said pawl lever, a holding pawl pivoted to one of saidmembers, springs urging said pawls upwardly into engagement with rackteeth on the. lower side of said bar, a hand lever fulcrumed to theframe and a link connecting said hand lever to said pawl lever,

Lilli letal 9. A jack comprising a frame, a lever fulcrumed to theframe, a lifting table supported by an arm of said lever, a rack barpivoted to another arm of the lever, means for slidably supporting saidbar comprising two transversely spaced similar members having coaxialtrunnions pivoted to said frame and having inwardly extending upper andlower guides engaging the upper and lower sides of said rack bar, abifurcated pawl lever straddling said bar and pivoted to said members, adriving -pavvl pivoted in the bifurcated lower end of said pawl leverand positioned to engage rack teeth on the lower side of said rack bar,a hand lever fulcrumed to the frame and ay link connecting said handlever to the upper end of said pawl lever.

10. The combination in a jack having a lifting table supporting lever atone end and a rack operably connected therewith and extending beyond theother end, of a driving pawl and a i holding pawl at said other endengaging teeth of said rack, springs urging said pawls'into engagementwith said teeth, each of said pawls having a laterally projecting pin, alever having a cam arm overlying said pins, and means for applying aspring pressure to said lever to cause said cam armto press against saidpins and move said .pawls out of engagement with said rack, said springpressure being insufficient to move either pawl when it is holding therack against a load on the table but being suincient to throw out thepawls when there is no load, said cam lever being so formed that whenthe table is loaded, operation of the driving pawl in a direction toraise the table and release the load on the holding pawl will permitsaid cam lever to throw out the holding pawl, whereupon reverseoperation of the driving pawl will permit lowering movement of the rackand will move the cam lever out of engagement with the holding pawl topermit the latter to engage the rack and relieve the driving pawl of theload, the driving pawl being thereupon thrown out of engagement with therack by the cam lever.

1l. The combination in a jack having a lifting table adjacent one end, alifting lever for raising and lowering said table and a rack operablyconnected to said lever and extending beyondl the other end, of drivingand holding pawls at said other end spring pressed into engagement withsaid rack, a lever having a cam arm adapted to engage said pawls, andmeans for applying spring pressure to` said lever` to cause said cam armto press on said pawls and throw them outof engagement with the rack,said pressure being insuiiicient to move either pawl when it is holdingthe rack against a load on the table but being sufficient to throw outthe pawls when the table is unloaded, said cam lever being so formedthat when said spring pressure is applied thereto and the table issustaining a load in raised position, operation of the driving pawl in adirection to raise the table and release the load on the holding pawlwill .permit said cam lever to throw out the holding pawl, whereuponreverse operation of the driving pawl will cause a correspondinglowering movement of the rack and simultaneously move said cam lever outof engagement with said holding pawl permitting the latter to reengagethe rack and relieve the driving pawl 'of the load, said cam armthereupon throwing the driving pawl out of engagement with the rack.

12. The combination in a jack having a wheeled frame and a lifting tableat one end of the frame and a rack adjacent the other end,

said rack being perably connected to raise and to lower said table, ofdriving and holding pawls positioned to engage said rack, a lever havinga cam arm adapted to engage said pawls, and means for applying springpressure to said lever to cause said cam arm to press on said pawls andthrow them out of engagement with the rack, said pressure beinginsufficient to move either pawl when it is holding the rack against aload on the table, but being sufficient to throw out the pawls when thetable is unloaded, said cam arm being so shaped that when springpressure is applied to said lever and the table is loaded, the holdingpawl will be thrown out of engagement with the rack bar when the drivingpawl approaches the limit of its table raising movement and will bepermitted to reengage the rack bar at an intermediate point in thereverse movement of the driving pawl and the driving pawl will be thrownout of engagement at the end of said reverse movement.

13. A jack comprising a frame, a lifting table mounted for parallelvertical movement adjacent one end of the frame, a rack bar extendingbeyondthe other end of the frame and operably connected to said table,driving and holding pawls for actuating said rack bar, a hand leverfulcrumed adjacent said other end of the frame and adjustably linkedr tosaid driving pawl, a lever having cam surfaces engaging said driving andholding pawls, a foot lever' fulcrumed to the frame adjacent said handlever, and spring means connecting said foot and cam levers, wherebywhen the foot lever is operated in one direction the cam lever will bearon said pawls with a predetermined yielding pressure, Which pressure issucient to disengage said pawls from said rack bar if there is no loadon the table but insufcient to disengage either pawl if it is holdingthe rack bar against a load on the table, said cam surfaces beingadapted to disengage thepawls successively on oscillation of the drivingpawl when the table is loaded, to eifect retrograde, or table lovverleTmovement of the rack bar.

14. In a jack, a pair of parallel side members, a wheel supporting axleconnecting the members at one end, a shaft connecting the members at theother end, brackets rising from the side members, a pair of bell crankrocking leversl pivoted in the brackets, a load support connecting thefree ends of the lever at one side, a raising bar mounted for rockingmovement between the side members and pivotally connected to the otherfree ends of the rocking lever, a jack handle pivoted on said shaft,means operated by said handle for moving the raising bar in onedirection to rock the levers to raise the load, and reversing means foreffecting a step-by-step lowering of the load by oscillation of thehandle about the shaft.

15. In a jack of the type in which the load support is pivoted to arocking lever, a substantially horizontal rack bar connected to operatethe lever, a pluraliy of spring held pawls each engaging the rack toprevent reverse movement of the rack bar while permitting quick advancemovement of the rack bar to bring the load support into contact with,the load, means for rocking one pawl to advance the rack bar toposition to be held by the other pawl, and means for holding said lastmentionedY pawl against the urge of its spring so the load may be takenby the first mentioned pawl for lowering movement said means beingeffective to move both Pie pawls simultaneously only when no load is onthe support.

16. In a jack, a rack bar, an inverted horizontal holding pawl on astationary axis below said bar, a rocker having a bifurcated lower endforking said bar and extending below the same, a pawl pivoted in thelower end of the rocker, means for resiliently holding the pawls incontact with the teeth of the rack to permit advance movement of therack while preventing reverse movement, means for rocking the rocker toadvance the rack bar by the rocker pawl to position when the holdingpawl will engage the next tooth, and spring pressed means 'to hold theholding pawl out of rack bar engaging position when the load is taken bythe rocker pawl so the rack bar may be retracted step-by-step whenloaded, and for holding both pawls out of rack bar engaging positionwhen not loaded, whereby when the rack bar is operatively connected to alever supported load engaging member or saddle, the saddle may bebrought quickly into position, the load raised and lowered slowly, andthe saddle will drop to lowest position when entirely freed of the load.

17. A jack comprising an elongated wheeled frame, a lifting tablemounted for parallel vertical movement adjacent the forward end of theframe, a lever having a forwardly extending arm supporting said tableand having a downwardly extending arm, a rack bar pivoted to saiddownwardly extending arm, a support slidably supporting said rack barand pivoted to said frame on an axis substantially parallel to thefulorum axis of said lever, a driving pawl lever pivoted to said supportand carrying a spring pressed pivoted pawl engaging said rack bar, aspring pressed holding pawl pivoted to said support, a hand leverfulcrumed to the frame and connected to said driving pawl lever, a leverhaving cam surfaces engaging said driving and holding pawls, a footlever fulcrumed to the frame adjacent said hand lever, and spring meansconnecting said cam and foot levers, whereby when the foot lever isoperated in one direction the cam lever will bear on said pawls with apredetermined yielding pressure, which pressure is insuiiicient todisengage said pawls if there is no load on the table but insufiicientto disengage either pawl if it is holding the rack bar against a load onthe table, said cam surfaces being adapted to disengage said pawlssuccessively on oscillation of the driving pawl, when the table isloaded, to effect lowering movement of the rack bar.

18. In a jack, a toothed member having downwardly extending teeth, aholding pawl on a stationary axis, a rocker. a pawl pivoted to therocker, means for resiliently holding the pawls upward into engagementwith said teeth to permit advance movement of the member whilepreventing reverse movement thereof, means for rocking the rocker toadvance the member by the rocker pawl to position when the holding pawlwill engage the next tooth, a horizontal cam arm, and spring pressedmeans adapted to urge said cam into engagement with said pawls to holdthe holding pawl out of tooth engaging position when the load is takenby the rocker pawl so the toothed member may be retracted step by stepwhen loaded, and for holding both pawls out of tooth engaging positionwhen unloaded, whereby when the toothed member is operatively connectedto a load supporting member or saddle, the saddle may be brought quicklyinto position by manually shifting said toothed member, the load raisedand lowered slowly, and the saddle will drop to lowest position whenentirely freed of the load.

EARL F. GREEN. FRANK A. GRAHAM.

